Is hyperventilating a good idea before holding your breath?
Not at all. First, it highly increases the risk of blacking out (i.e., losing consciousness) because it delays the natural alarm system in the body. Secondly, you cannot put extra oxygen into your bloodstream. Once you are fully saturated (100 percent), it does not matter how crazy you might breathe or blow out—it does not change anything. Lastly, you increase heart rate and metabolism considerably which is not very smart.
But what you can do is to increase Vital Capacity. And now we even have scientific studies and articles backing up my statement. So by using a technique called “lung packing,” it is possible to hold much more air. In my case I can increase to over 14 liters. But it can be very dangerous and should only be done under competent guidance.